"Clever" fix to handle case of deletion to window start causes "point

"Clever" fix to handle case of deletion to window start causes "point
not visible at end of redisplay" error.  This happens when the start
mark is clobbered and the new start is not near enough to the point;
for example by deleting some text, then replacing it with itself.

Also, somehow UPDATE-OUTLINES! is getting called with FORCE-REDRAW?
and the CURRENT-START-MARK both false, which shouldn't be able to
happen; compiled code deals with this by treating #f as 0.  This
change fixes this unusual case.